Dualities and Hidden Supersymmetry in String Quantum Cosmology

A supersymmetric approach to string quantum cosmology based on the non-compact, global duality symmetries of the effective action is developed. An N=2 supersymmetric action is derived whose bosonic component is the Neveu-Schwarz/Neveu-Schwarz sector of the $(d+1)$--dimensional effective action compactified on a $d$--torus. A representation for the supercharges is found and the form of the zero-and one-fermion quantum states is determined. The purely bosonic component of the wavefunction is unique and manifestly invariant under the symmetry of the action. The formalism applies to a wide class of non-linear sigma-models.Comment: 18 pages, plain Latex, no figure

Stretching the Inflaton Potential with Kinetic Energy

Inflation near a maximum of the potential is studied when non-local derivative operators are included in the inflaton Lagrangian. Such terms can impose additional sources of friction on the field. For an arbitrary spacetime geometry, these effects can be quantified in terms of a local field theory with a potential whose curvature around the turning point is strongly suppressed. This implies that a prolonged phase of slow-roll inflation can be achieved with potentials that are otherwise too steep to drive quasi-exponential expansion. We illustrate this mechanism within the context of p-adic string theory.Comment: 4 page

Inflationary Cosmology and Oscillating Universes in Loop Quantum Cosmology

We study oscillatory universes within the context of Loop Quantum Cosmology. We make a comparative study of flat and positively curved universes sourced by scalar fields with either positive or negative potentials. We investigate how oscillating universes can set the initial conditions for successful slow-roll inflation, while ensuring that the semi-classical bounds are satisfied. We observe rich oscillatory dynamics with negative potentials, although it is difficult to respect the semi-classical bounds in models of this type.Comment: 7 pages, In Press Int. Mod. Phys.

Low-energy quantum string cosmology

We introduce a Wheeler-De Witt approach to quantum cosmology based on the low-energy string effective action, with an effective dilaton potential included to account for non-perturbative effects and, possibly, higher-order corrections. We classify, in particular, four different classes of scattering processes in minisuperspace, and discuss their relevance for the solution of the graceful exit problem.Comment: Extended version to appear in the Review section of Int. J. Theor. Phys. A 13 (1998). The new permanent address is added. An updated collection of papers on the pre-big bang scenario is available at http://www.to.infn.it/~gasperi

Study of orbiter/payload interface communications configuration control board directive from an operational perspective

Orbiter/payload data and communications interface was examined. It was found that the Configuration Control Board Directive (CCBD) greatly increases the capability of the orbiter to communicate with a wide variety of projected shuttle payloads. Rather than being derived from individual payload communication requirements, the CCBD appears to be based on an operational philosophy that requires the orbiter to duplicate or augment the ground network/payload communication links. It is suggested that the implementation of the CCBD be reviewed and compared with the Level 1 Program Requirements Document, differences reconciled, and interface characteristics defined